alloc::heap::__rust_reallocate

unsafe extern fn __rust_reallocate(ptr: *mut u8, old_size: usize, size: usize, align: usize) -> *mut u8

Unstable (heap_api #27700)

: the precise API and guarantees it provides may be tweaked slightly, especially to possibly take into account the types being stored to make room for a future tracing garbage collector